Distribution of Anopheles mosquito species, their vectorial role and profiling of knock-down resistance mutations in Botswana
Knowledge of vector species composition and monitoring their change over time is critical to evaluate malaria transmission and assess control interventions. This is especially important in countries such as Botswana, where malaria transmission is subjected to fluctuations due to climate variability....
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Veröffentlicht in: | Parasitology research (1987) 2020-04, Vol.119 (4), p.1201-1208 |
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Zusammenfassung: | Knowledge of vector species composition and monitoring their change over time is critical to evaluate malaria transmission and assess control interventions. This is especially important in countries such as Botswana, where malaria transmission is subjected to fluctuations due to climate variability. Another important aspect that impacts vector populations is the insecticide resistance. In order to assess species composition and the presence of mutations associated with insecticide resistance,
Anopheles
specimens from larval samplings and indoor pyrethrum spray sheet collections were analysed. A total of 349
Anopheles
were screened by morphology and PCR as belonging to the
An. gambiae
complex and
An. funestus
group. Specimens were subsequently analysed for human blood meal and
Plasmodium
index. Finally, knock-down resistance polymorphisms were assessed.
Anopheles arabiensis
accounted for the majority of specimens collected through larval (96.7%) and pyrethrum spray sheet collection (87.4%) across all sampling sites, and this species was the only one found positive for human blood and for
P. falciparum
. Other
Anopheles
species were collected in small numbers by pyrethrum spray catches, namely
An. quadriannulatus
,
An. longipalpis
type C and
An. parensis
. The authors speculate on changing climate patterns and their possible impact on species composition. The
kdr
assay revealed that
Anopheles
mosquitoes were homozygous wild type for both L1014F (
kdr-w
) and L1014S (
kdr-e
) mutations. These results highlight the unique vectorial role of
An. arabiensis
in Botswana and indicated that even with prolonged use of pyrethroids and DDT, the mosquito population has not developed
kdr
mutations, despite some in vivo evidence of insecticide resistance. |
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ISSN: | 0932-0113 1432-1955 |
DOI: | 10.1007/s00436-020-06614-6 |